The invention relates to an apparatus for wire-stitching print products, compiled from gathered signatures, and for trimming the print products along the open side edges. The apparatus includes a first gathering and wire-stitching machine provided with a first wire-stitching unit and a first cutter which is installed downstream from the first gathering and wire-stitching machine. A second gathering and wire-stitching machine can be added in-line with the first gathering and wire-stitching machine and is provided with a second wire-stitching unit. The apparatus also includes a second cutter installed downstream from the second gathering and wire-stitching machine. The apparatus furthermore includes a transfer element positioned between the first and second gathering and wire-stitching machines.
A tandem arrangement of gathering and wire-stitching machines of the aforementioned type is disclosed in European Patent Document EP 1 232 978 A1, wherein the first gathering and wire-stitching machine is also called a slave and the second gathering and wire-stitching machine is also called a master. Both gathering and wire-stitching machines are respectively provided with a gathering chain or other suitable conveying device, at least one feeder, one wire-stitching unit, a cutting device, an ejection device and a cross stacker. The resulting print products are stacked in the cross stacker. The cutters may be three-knife trimmers and are also called trimmers. The ejection device for transferring the print products to the first cutter is arranged downstream from the first wire-stitching unit. This tandem arrangement of gathering and wire-stitching machines can optionally be used for a so-called solo operation or a tandem operation.
For the solo operation, the two gathering and wire-stitching machines work separately and the transfer element is therefore not in use. The ejection device for the first gathering and wire-stitching machine is turned on. Each cutter is provided with an asynchronous motor and each wire-stitching unit is provided with a servomotor, wherein the servomotor respectively follows the asynchronous motor and operates the gathering chain as well as the feeders for the separate gathering and wire-stitching machine.
For the tandem operation, the two gathering and wire-stitching machines are connected to each other via the transfer element. They operate synchronously, but the asynchronous motor for the first cutter and the ejection device for the first cutter are shut down. During the tandem operation, the first cutter cannot be operational because the knives would otherwise become dull. The servomotor for the first wire-stitching unit follows the asynchronous motor of the second cutter. This arrangement has the disadvantage that it is not possible to pre-stitch products with the first wire-stitching unit. For the tandem operation, the print products pass through the first wire-stitching unit while this unit is shut down and are thus not stitched. If a pre-stitching of the products is desired, they must be stitched in an additional gathering and wire-stitching machine and must be fed in a second time.